1. Field of Invention
The present invention relates to a driving circuit to drive an electro-optical panel, such as a liquid crystal panel, etc., an electro-optical device, such as a liquid crystal display device, etc. including the electro-optical panel and the driving circuit, and an electronic apparatus, such as a liquid crystal projector, etc. including the electro-optical device.
2. Description of Related Art
Related art examples of such driving units for an electro-optical panel include a data line driving circuit to drive data lines of the electro-optical panel, a sampling circuit, a precharge circuit, and others. The data line driving circuit outputs sequential transmission signals output from a shift register circuit thereof as sampling pulses to the sampling circuit. In response to the sampling pulses, the sampling circuit samples image signals of image signal lines and supplies the sampled image signals to the data lines.
The writing of image signals to the data lines by means of the sampling circuit causes no problem in electro-optical panels having low driving frequencies and employing an active matrix driving method. However, when the image fineness is enhanced or the driving frequency is raised due to a general requirement for excellent display quality, influence of wire capacity of the data lines, etc. cannot be neglected. Specifically, with the raising of the driving frequency, lack of driving ability of the data line driving circuit or lack of writing ability of the sampling circuit is elicited. Such lack of writing ability, etc. causes image defects, such as ghosts, etc.
For this reason, in the related art, the lack of driving ability of the data-line driving circuit or the lack of writing ability of the sampling circuit was compensated for, by writing a precharge signal of a predetermined potential level, for example, corresponding to a gray color or an intermediate color to the data lines before writing image signals to the data lines.
In order to lower the driving frequency or reduce a fly-back period, for example, for image display corresponding to a high vision the driving frequency of which is high and the fly-back period of which is short, a precharge circuit called a transmission precharge or sequential precharge circuit has been developed. According to such a transmission precharge circuit, right before writing the image signals to the data lines, by performing the sequential operation of the precharge circuit prior to the sequential operation of the sampling circuit, the precharge can be efficiently performed for a relatively short time.
In the related art transmission precharge circuit, on a substrate, a sampling circuit and a data-line driving circuit including a shift register circuit to drive the sampling circuit are arranged at one end of the data lines, and a precharge circuit and a precharge-circuit driving circuit including a shift register circuit to drive the precharge circuit are arranged at the other end of the data lines. In peripheral areas around an image display area in which the data lines are arranged on the substrate, the sampling circuit and the data-line driving circuit to drive the sampling circuit are arranged, for example, in the vicinity of the lower side of the image display area, and the precharge circuit and the precharge-circuit driving circuit to drive the precharge circuit are arranged, for example, in the vicinity of the upper side of the image display area. For this reason, a technical problem that it is very difficult to miniaturize a substrate or the whole device is basically caused due to employing the precharge circuit. Specifically, since separate circuits are provided at both ends of the data lines, arrangement of various wires on the substrate becomes difficult. Even when the various circuits are constructed as external IC circuits, problems, such as increase of the number of ICs, difficulty in securing mount areas, difficulty in manufacturing processes, etc. are caused.